Apparatus for coating work pieces with thermoplastic material

ABSTRACT

Apparatus for coating sheet work pieces with thermoplastic adhesive is provided comprising a table, a portion of which is arranged to be heated for warming the thermoplastic adhesive material for light adherence to work pieces and upper and lower pressure rolls operable progressively to heat and press the assembly, the lower roll being provided with heating means for softening the adhesive material while the upper roll is deformable for pressing the layer of adhesive material firmly against the work pieces and of stripped material adjacent the peripheries of the work pieces. Preferably the apparatus includes means for tensioning backing material for the adhesive film and means for taking up the stripper material after passage through the presser rolls.

Aug. 15, 1972 T. J. L. CLARKE ETAL 3,684,628 APPARATUS FOR COATING WORKPIECES WITH THERMOPLASTIC MATERIAL Original Filed Sept. 6, 1967 2Sheets-Sheet l Au 15, 1972 T. J. L. CLARKE E'I'AL 3,684,628

APPARATUS FOR COATING WORK PIECES WITH THERMOPLASTIC MATERIAL OriginalFiled Sept. 6. 1967 2 Sheets-Sheet 2 u 1 w |H 4" 7 H n m I J 1 I l a|Hu. x J 1i w f/z l 7 n "I 1" u n "1, W l |||u| J U H N u h W 1 H m M hh n 3 T n u u n n u u u H n I w? Lu i n u U 0 0 4, 11.: L.:: n H i n 1 mn Wm r 4 M I. I. ll. Z 2 d 0 i r \l W w H 7 n w T mlinnl 2 t lw uflUnited States Patent 3,684,628 Patented Aug. 15, 1972 3,684,628APPARATUS FOR COATING WORK PIECES WITH THERMOPLASTIC MATERIAL Terence J.L. Clarke, Leicester, England, and Ivor Evans, deceased, late ofLeicester, England, by lush: V. Evans, administratrix, Cossington,England, assignors to United Shoe Machinery Corporation, Boston, Mass.

Original application Sept. 6, 1967, Ser. No. 667,323, now Patent No.3,580,774. Divided and this application Jan. 12, 1970, Ser. No. 7,438

Int. Cl. B30b 15/34; B3211 31/20 US. Cl. 156-583 3 Claims ABSTRACT OFTHE DISCLOSURE Apparatus for coating sheet work pieces withthermoplastic adhesive is provided comprising a table, a portion ofwhich is arranged to be heated for warming the thermoplastic adhesivematerial for light adherence to work pieces and upper and lower presserrolls operable progressively to heat and press the assembly, the lowerroll being provided with heating means for softening the adhesivematerial while the upper roll is deformable for pressing the layer ofadhesive material firmly against the work pieces and the layer ofstripper material adjacent the peripheries of the work pieces.Preferably, the apparatus includes means for tensioning backing materialfor the adhesive film and means for taking up the stripper materialafter passage through the presser rolls.

This is a division of application Ser. No. 667,323, filed Sept. 6, 1967,now US. Pat. No. 3,580,774.

BACKGROUND OF THE INVENTION This invention relates to the adhesivebonding of parts and more particularly is concerned with improvements inor relating to coating work pieces with adhesive material and apparatusfor use therein. The invention is illustrated as applied to the bondingof pieces of sheet material in the assembly of parts of shoe uppers. Theword shoe is used herein generically to indicate outer footweargenerally.

In the manufacture of shoes of a type which do not wholly enclose thefoot of a wearer but leave the heel exposed and the forepart partlyvisible through openings in the vamp, that is to say of a type of whichsandals and sling-back shoes are examples, it is customary to cut outfor each shoe a number of pieces of leather or other material suitablefor the outer integument of the shoe upper, the shapes varying inoutline, some of them being elongated and strap-like, cutting similarlyshaped pieces from thin leather or other suitable lining material,coating one or both sets of pieces with a liquid adhesive composition,for example a neoprene rubber solution, and allowing the coatings todry, and reactivating the coatings by heat, for example, generated by ahigh-frequency electric field, and bonding the pieces together.

The application of liquid adhesive compositions to pieces of a shoeupper, especially where the pieces, as is usually the case with thepieces of lining material in carrying out a procedure as just referredto, are narrow and flimsy, tends to be laborious and messy.

SUMMARY OF THE INVENTION It is one of the objects of the presentinvention to provide an improved apparatus for coating sheet materialwork pieces with adhesive material which method will overcome theaforesaid difiiculties.

To this end and in accordance with a feature of the present invention,there is provided apparatus comprising a table for supporting a layer ofsheet material carrying Work pieces in engagement with a layer ofthermoplastic adhesive material. At least a portion of the tablesuitably is arranged to be heated for warming the layer of thermoplasticadhesive supported thereon to effect light adherence of the work piecesengaged therewith. The apparatus includes upper and lower pressure rollsoperable to heat and press an assembly comprising the work piecesdisposed between a layer of stripper material and the layer of saidthermoplastic material, the lower roll being provided with heating meansfor softening the adhesive material. The upper roll is deformable forpressing the stripper layer firmly against the adhesive layer at theperipheries of the work pieces. Preferably, the apparatus includestensioning means for backing material fed through the presser rollersand means for supporting dispensing and take-up reels for handling thestripper material 'which removes excess adhesive.

The invention will be described further in connection with the attacheddrawings in which:

FIG. 1 is a front elevation partly in section of apparatus embodying thepresent invention; and

FIG. 2 is a right elevation on a slightly enlarged scale and with atable removed of the apparatus shown in FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The apparatus of the presentinvention is particularly useful in carrying out the following methodwhich is also described in the above mentioned patent. In carrying outthe method work pieces are assembled with a layer of stripper materialand a layer of adhesive material which is non-tacky at room temperaturebut which becomes tacky and then activated upon the application of heat.In the preferred mode in carrying out the method, an adhesive filmsuitably about .002" to .004" thick is carried as a coating on a layerof backing material, suitably silicone release paper. However, theadhesive may be provided in the form of an unsupported film or a layerof powdered adhesive. Where the method is practiced without the use of alayer of backing material, a layer of stripper material such as cheapnewsprint is fed across a warm table carrying work pieces thereon whilea layer of adhesive is dipsosed over the 'WOl'k pieces and the strippermaterial. The assembly is then subjected to heat and pressure foractivation and bonding of the adhesive layer to the work pieces andstripper material. The bonded assembly may be stored for future use or,if the work pieces are then to be bonded to other parts, the work piecesmay be removed from the stripper material while the adhesive is inheat-softened condition. Because of the strong attachment of theadhesive to the stripper material, and the application of pressure, thework pieces when picked off, have an adhesive coating thereon withclearly defined margins.

In a preferred embodiment of the method the adhesive is supportedagainst the work pieces and stripper material by a layer of backingmaterial, suitably silicone release paper to which the adhesive adheresless strongly than to the stripper material. In those mode of carryingout the method, a layer of backing material carrying as a coatingthereon a layer of adhesive is drawn across a Warm table with the workpieces superimposed thereon. A layer of stripper material is disposedover the Work pieces and adhesive layer and the assembly heated andpressed. The layer of stripper material is separated from the backingmaterial while the adhesive is in heat-softened condition, leaving thecoated work pieces on the backing material and removing the surplusadhesive on the stripper material.

It is also within the purview of the invention to provide for the Workpieces to be carried on a layer of stripper material while a layer ofthermoplastic adhesive material is applied to the exposed surfaces ofthe work pieces and stripper material and in which a layer of backingmaterial, suitably silicone release paper, is employed for supportingthe layer of adhesive against the work pieces and stripper materialduring the application of heat and pressure and thereafter serves toretain thereon the coated work pieces while the stripper material isremoved with excess adhesive.

Referring now to the drawings, the apparatus comprises a frame 110arranged to stand on the floor. The frame provides left hand and righthand horizontal tables 112, 113 respectively with a platform 117 of theframe 110 therebetween. Heated blocks 114, 115 are inset in the tables112, 113 respectively.

Similarly secured to the platform 117 of the illustrative apparatus andconnected by a horizontal plate 125 are housings 124 by which arecarried upper and lower pressure rolls 118 and 120 respectively. Theupper roll 118 has a surface layer of silicone rubber and is free torotate in bearings mounted in blocks 121 (only one visible in thedrawings), the blocks 121 being mounted for up and down movement inguideways 123 (only one visible in the drawings) in the housing 124. Theblocks 121 can be moved downwards by air under pressure admitted tospring return air motors 1'26 mounted on the plate 125 upon depressionof a foot pedal (not shown).

The lower presser roll 120 of the illustrative apparatus is a smoothsteel one mounted in the housings 124 vertically below the roll 118 onthe shaft 130 at such a height that the highest point of the roll islevel with and close to the surface of the left hand table 112. The roll120 is arranged to be heated by a block 140 having a semi-cylindricalupper surface and heated in turn by electrical elements not shown.

Mounted on the platform 117 is a speed reduction unit 136 driven by abelt 134 from an electric motor 138 secured to the underside of theplatform 117. An output shaft 137 of the speed reduction unit 136 iscoupled to the shaft 130.

Also secured to the platform 117 are blocks 170 by which is supportedfor rotation a shaft 172 parallel to the shaft 130. A smooth steelroller 174 is secured to the shaft 172, the shaft being at such a heightthat the highest point of the roller is level with and close to thesurface of the right hand table 113. The shaft 172 is arranged to bedriven by gears (not shown) from the shaft 130 at the same number ofrevolutions per minute as the shaft 130; however the diameter of theroller 174 is slightly greater than that of the roll 120.

Two arms 184 are pivotally mounted on bearing pins 186 and are rigidlyconnected by a bar 185. An axle 187 is rotatably mounted in bearings(not shown) carried in the arms 184 and is parallel to the roller 174.Secured to the axle 187 and spaced apart therealong (see FIG. 2) are tworollers 182 of neoprene rubber. The rollers 182 are urged toward theroller 174 by springs 188 extending between the arms 184 and thehousings 124.

A scraper bar 218 is carried by brackets 220 secured to the bar 185 andlies between the two rollers 182 and a scraper edge 222 (FIG. 2) of thescraper bar 218 lies between the rollers 118 and 182. The brackets 220are electrically insulated from the bar 185 and the brackets areconnected by Wires 221 to an electrical supply. In the operation of theillustrative apparatus an electrical current (for example 100 amps at 2volts) is passed through the brackets 220 along the scraper bar 218whereby to heat the bar to an elevated temperature of, for example, 130C. As seen in FIG. 2 secured to a plate 223 secured to the blocks 170 atthe rear of the illustrative apparatus is a small spring return airmotor 224 having a plunger 226 arranged, when air is supplied to themotor 224 to bear on one of the arms 184 to hold the arms 184 in araised position with the rollers 182 out of contact with the roller 174.

The rollers 174 and 182 are tensioning rollers of the illustrativeapparatus.

Supports (not shown) for a dispenser reel (not shown) carryingadhesive-coated release paper 193 and supports (not shown) for a take-upreel (not shown) are mounted on the frame 110 and the take-up reel isarranged to be driven, in the operation of the illustrative apparatus,through a slipping clutch from an electric motor (not shown) mounted onthe frame 110 beneath the table 113, the dispenser reel being brakedsufficiently to keep the release paper taut in the operation of theillustrative apparatus.

Secured to the plate 125 are two support pillars 302 each carrying a bar303, the bars 303 being parallel to each other. Shafts 304, 306 arerotatably mounted in bosses 305, 307 respectively carried by the bars303. A dispenser reel 308 for newsprint 310 is secured to the rod 384for rotation therewith and the rod is arranged to be braked, in theoperation of the illustrative apparatus, by

braking means (not shown). A take-up reel 312 for the newsprint issecured to the shaft 306 for rotation therewith. The reels 308 and 312are removable from the shafts 304, 306 so that they may be readilyreplaced by other reels.

Still referring to FIG. 2, it shows a post 318, secured to the platform117, at an upper end of which a shaft 320 is rotatably mounted inbearings (not shown) one set in the post and another set carried at aright hand end (viewing FIG. 2) of an arm 321. Keyed to the shaft 320 ata left hand end thereof (viewing FIG. 2) is a pulley 322 and keyed tothe shaft 320 to the right of the post 318 is another pulley 324. Apulley 326 is freely rotatable on the shaft 320' and is carried thereonto the right of the pulley 324. The pulley 326 is driven, in theoperation of the illustrative apparatus, by a belt 328 passing round apulley 330 secured to an output shaft 331 of the speed reduction unit136. A friction clutch lining 332 is bonded to a face of the pulley 326adjacent the pulley 324. Mounted at the right hand end of the arm 321 isa spring-return air motor 334 which on supply of air under pressure inthe operation of the illustrative apparatus moves the pulley 326 to theleft (viewing FIG. 2) and thus the lining 332 into engagement with thepulley 324 whereby to drive the pulley 324 and thus the shaft 320 fromthe pulley 326.

A slipping clutch unit 336 is supported on the shaft 306 which is driventhrough the clutch unit 336 by a pulley 238 driven by a belt 340 whichpasses round the pulley Returning to FIG. 1 identical guides 342 for therelease paper 193 are secured to the tables 112, 113 adjacent theplatform 117.

Two brackets 344 (only one visibile in the drawings) are secured to thetable 112 between the guide 342 and the platform 117. Arms 346 arepivotally mounted on the brackets 344 (one on each bracket) and support,for free rotation about an axis parallel to the axis of the roll 120, aroller 348 having a silicone rubber surface. The roller 348 is arrangedto lie under its own weight on the adhesive coated release paper 193 toassist in preventing the paper 193 from creasing between the edge of thetable 112 and rolls 118, 120.

It will be understood that means may be provided in the illustrativeapparatus for varying the temperature of the heated blocks 114, in thetables 112, 113, the block 140 and the scraper bar 218, and means isprovided for varying the speed of rotation of the roll and the roller174. Means may also be provided for varying the pressure exerted by theroll 118.

Conveniently in the operation of the illustrative apparatus, in applyinga layer of a heat-softenable adhesive composition to a piece of sheetmaterial, the release paper 193 used comprises a paper base sheettreated with a silicone release agent. The release paper is coated onone side with a layer of uniform 0.002" thickness of an adhesive basedon ethylene vinyl acetate copolymer. The adhesive layer is applied to acentral portion of the paper leaving marginal portions of the paperuncoated; the rollers 182 are arranged to run on these marginalportions.

In setting up the illustrative apparatus a reel of this adhesive-coatedrelease paper 193 is first mounted on the support for the dispenser reeland the paper is led over an idler roller (not shown) across the table112 (including the heated block 114 thereof) and through the first ofthe guides 342, between the roller 348 and the table 112, between therolls 118 and 120 and then the rollers 174 and 182, through the secondof the guides 342 and thence over the table 113 (including the heatedblock 115 thereof) over another idler roller (not shown) onto a take-upreel (not shown). The dispenser reel 308 (carrying newsprint 310) ismounted on the shaft 304 and newsprint 310 is led from the reel 308round the roller 118 to the take-up reel 312 mounted on the shaft 306.The block 140 and the heated blocks 114, 115 in the tables 112, 113 areheated to desired temperatures. Suitably for example, the block 114 maybe heated to about 70 C. while the roll 120 and block 140 are heated toabout 140 C. Work pieces of lining material are then placed on theadhesive coated paper 193 in spaced array, overlying the block 114.

When the surface of the paper immediately in front of the operator issufficiently covered, the operator presses the foot pedal actuating avalve (not shown), actuation of which admits air to the air motors 126causing the upper roll 118 to descend so that it spreads into contactwith the work, the work being thus pressed between the upper roll 118and the lower roll 120 (the lower roll 120 rotates continuously whenpower is supplied to the illustrative apparatus). The adhesive-coatedrelease paper 193 with the lining material thereon and the newsprint 310are thus fed between the rolls 118 and 120 by rotation of the roll 120.Actuation of the valve by the foot pedal also causes air to be actuatedto the air motor 334 thus to drive the pulley 322 and drive through theclutch unit 336 the take-up reel 312.. Actuation of the valve by thefoot pedal also releases air from the air motor 224 and allows the arms184 to be urged downwardly by the springs 188 so that the rollers 182contact the marginal portions of the release paper 193 and press themagainst the roller 174 (which is driven from the roll 120), thetensioning rollers 174, 182 drawing the paper 193 (carrying the piecesof lining material) onwards in a straight line, the newsprint 210carrying excess adhesive being drawn up onto the take-up reel 312. Thescraper bar 218 acts to break any strings of adhesive stretching betweenthe newsprint 210 and release paper 193 as they are separated. Apressure switch is also operated on actuation of the valve, the pressureswitch closing a circuit to start the electric motor mounted beneath thetable 113 to drive, through the slipping clutch, the take-up reel forthe release paper 193.

When the pieces of lining material are removed from the release paperthey are found to have a uniform coating of adhesive on one sidethereof.

Having thus described our invention, what we claim as new and desire tosecure by Letters Patent of the United States is:

1. Apparatus for coating sheet material work pieces with thermoplasticadhesive comprising, in combination a table for supporting a layer ofsheet material carrying work pieces in engagement with a layer ofthermoplastic adhesive material, upper and lower presser rolls mountedadjacent the table for engaging opposite sides of an assembly comprisingsaid work pieces disposed between said layer of thermoplastic materialand a layer of stripper material, means for heating one of said rollsfor softening said layer of thermoplastic adhesive material, the otherroll having at least a peripheral portion thereof deformable forpressing the layer of adhesive into engagement with said work pieces andwith the stripper material in areas adjacent the peripheries of the workpieces, means for driving at least one of said rolls for progressivelyeffecting heating and pressing along the assembly, and means effectiveafter said roller engagement means for separating the stripper materialfrom the sheet material and work pieces to remove therewith the adhesivein engagement with the stripper material in areas adjacent theperipheries of the work pieces.

2. Apparatus as in claim 1 and additionally comprising means for heatinga portion of the supporting surface of said table to warm the adhesivebefore the roller heating means to effect light adherance with said workpieces before said pressing and heating means.

3. Apparatus as in claim 1 and additionally comprising means comprisinganother set of rollers driven at a peripheral speed greater than that ofsaid rolls for applying tension to at least one layer of said assemblyafter said assembly passes through said presser rolls.

References Cited UNITED STATES PATENTS 3,079,619 3/1963 Conrose 156-584UX 3,404,057 10/1968 Hieart 156584 X 3,471,351 10/1969 Fuchs 1565'83 X3,415,705 12/1968 Ettre 156-584 X 3,415,706 12/1968 Ettre 156--584 XBENJAMIN A. BORCHELT, Primary Examiner J. J. DEVITT, Assistant ExaminerU.S. Cl. X.R. 15 6-5 84

